Abstract
Purpose
The differential diagnosis of ACTH-dependent Cushing’s syndrome remains a challenge in clinical practice. The aim of the present study was to assess the diagnostic performance of pituitary dynamic enhanced MRI(dMRI), high-dose dexamethasone suppression test༈HDDST༉and combination of both tests in patients with ACTH-dependent Cushing’s syndrome.
Methods
119 consecutive cases with surgery confirmed ACTH-dependent Cushing’s syndrome were enrolled: 101 patients with proven Cushing’s disease and 18 patients with proven ectopic ACTH syndrome. All patients underwent pituitary dMRI and HDDST. The sensitivity and the specificity of pituitary dMRI, HDDST, and combination of both tests were calculated.
Results
The sensitivity and specificity of the pituitary dMRI for the diagnosis of Cushing’s disease was 80.2% and 83.3% respectively, and the positive predictive value was 96.4%. The sensitivity and specificity of HDDST was 70.3% and 77.8%, and the positive predictive value was 94.7%. Regarding the combination of both tests, the combined criteria of a more than 50% suppression of serum cortisol in HDDST and a positive finding in pituitary dMRI had given a high specificity of 94.4% and a sensitivity of 59.4%. The combined criteria of a greater than 68% suppression in HDDST and/or a positive finding in pituitary dMRI, provide a sensitivity of 86.1% and a specificity of 83.3%.
Conclusions
Pituitary dMRI was superior to HDDST in the differential diagnosis of ACTH-dependent Cushing’s syndrome. HDDST was recommended to combined with pituitary dMRI in the diagnosis process because of the significantly increased specificity of the combination.
EffectivenessVersusEfficacy: The Limited Value in Clinical Practice of High Dose Dexamethasone Suppression Testing in the Differential Diagnosis of Adrenocorticotropin-Dependent Cushing’s Syndrome